CN105634300A

CN105634300A - Piezoelectric energy collection rectifier for open-circuit type optimization of turnover time

Info

Publication number: CN105634300A
Application number: CN201610037866.9A
Authority: CN
Inventors: 邝继顺; 吴了; 尤志强; 凌纯清
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2016-01-21
Filing date: 2016-01-21
Publication date: 2016-06-01

Abstract

The invention discloses an open-circuit piezoelectric energy collection rectifier with optimized flipping time, which comprises two active diodes, two switches, an inductor, a peak detection and a digital circuit control module. One pair of active diodes performs complementary on/off operations. Once a diode detects a zero-crossing point of current flowing from positive to negative, the diode is turned off, and the other diode is turned on. The active diode outputs a corresponding one-bit switch status signal. One of the peak detection and digital circuit control modules receives the switch state signal of the active diode, detects the peak voltage of the cathode of the active diode, and outputs a pulse signal with an optimized pulse width. Two of the switches receive the pulse signal from the peak detection and digital circuit control module to perform on/off operation. One of the inductors is connected in series with the piezoelectric device and connected to the input terminal of the rectifier. Under the control of the peak detection and digital circuit control module, the capacitor voltage of the piezoelectric device is optimally reversed, and energy is transmitted to the load at the same time.

Description

An Open-circuit Piezoelectric Energy Harvesting Rectifier with Optimized Turnover Time

技术领域technical field

本发明主要涉及机械能转换为电能的领域，特指一种开路式优化翻转时间的压电能量采集整流器。The invention mainly relates to the field of converting mechanical energy into electric energy, in particular to an open-circuit piezoelectric energy harvesting rectifier with optimized flipping time.

背景技术Background technique

基于压电式悬梁臂结构的能量采集器因其具有低成本、高功率密度、高扩展性等优势，使它非常适用于小型化振动能量采集系统。但小型化能量采集系统可获得的功率非常低，一般低于1毫瓦，并且在能量传输过程造成的损耗进一步降低了到负载的净能量。因此，一个低功耗的电路设计必不可少。另外，由于从压电传导器输出的电压为交流电，而负载需要一个稳定的直流电压，因此还需要一个交流转直流的整流器。Energy harvesters based on piezoelectric cantilever arm structures are very suitable for miniaturized vibration energy harvesting systems due to their low cost, high power density, and high scalability. However, the available power of miniaturized energy harvesting systems is very low, generally less than 1 milliwatt, and the losses caused in the energy transmission process further reduce the net energy to the load. Therefore, a low power consumption circuit design is essential. In addition, since the output voltage from the piezoelectric conductor is AC, and the load requires a stable DC voltage, an AC-to-DC rectifier is also required.

图1表示的是一个典型的使用全桥整流器的压电能量采集电路，该电路中被动二极管固有的前向电压降约为0.7伏，在传输压电端能量到负载时会引入过多的导通损耗，而且为了传输能量到负载，压电端电压差必须大于两个二极管前向电压降的和，即约1.4伏，从而限制了该电路在小型压电能量采集的应用。Figure 1 shows a typical piezoelectric energy harvesting circuit using a full-bridge rectifier. The inherent forward voltage drop of the passive diode in this circuit is about 0.7 volts, which will introduce too much conduction when transferring energy from the piezoelectric terminal to the load. In order to transmit energy to the load, the voltage difference between the piezoelectric terminals must be greater than the sum of the forward voltage drops of the two diodes, which is about 1.4 volts, which limits the application of this circuit in small piezoelectric energy harvesting.

另一方面，如图1所示，因为压电设备输出电抗呈现大的容性，在每半个振动周期压电端电压翻转时，都会有电荷浪费在对压电传导器电容的充放点过程中。为了避免电荷浪费，更多地提取来自压电端的能量，人们提出了各种各样的非线性方法。图2表示的是一种典型的串联电感同步开关能量采集电路，也称为串联电感开关能量采集技术。该技术使用一个串联的电感和开关与压电传导器串联作为全桥整流器的输入。在振动周期的大部分时间内开关截止，压电电荷聚集在电容上形成缓缓上升的电压，一旦达到电压峰值，即压电端输出电流过零点时，开关短暂导通，储存在电容上的一部分能量被传递到负载端，另一部分能量返回压电端，并在压电电容上形成翻转的电压。一旦剩下的能量全部返回电容，开关再次截止，传导器的反向电流在下半个振动周期对电容反向充电，并重复上述过程。On the other hand, as shown in Figure 1, because the output reactance of the piezoelectric device presents a large capacitance, when the piezoelectric terminal voltage is reversed every half of the vibration cycle, there will be a waste of charge at the charging and discharging point of the piezoelectric conductor capacitance in process. In order to avoid charge waste and extract more energy from the piezoelectric end, various nonlinear methods have been proposed. Figure 2 shows a typical series inductor synchronous switch energy harvesting circuit, also known as series inductor switch energy harvesting technology. This technique uses a series inductor and switch in series with a piezo conductor as the input to a full bridge rectifier. During most of the vibration cycle, the switch is turned off, and the piezoelectric charge accumulates on the capacitor to form a slowly rising voltage. Once the voltage peak value is reached, that is, when the output current of the piezoelectric terminal crosses zero, the switch is briefly turned on, and the stored on the capacitor A part of the energy is transferred to the load terminal, and another part of the energy is returned to the piezoelectric terminal, and an inverted voltage is formed on the piezoelectric capacitor. Once the remaining energy is fully returned to the capacitor, the switch is turned off again, and the reverse current of the conductor reversely charges the capacitor in the second half of the vibration cycle, and the above process is repeated.

尽管图2所示的电路解决了电荷浪费的问题，但其使用了被动二极管，增加了导通损耗，限制了压电端输出电压幅度，且开关的导通时间受电感、压电端电容、甚至负载的影响，导通时长的精确控制需要额外的人为调节，不合适的开关导通时长将大大降低整流器的提取效率。考虑到这些问题，该电路不适用于小型的压电能量采集。Although the circuit shown in Figure 2 solves the problem of charge waste, it uses a passive diode, which increases the conduction loss and limits the output voltage amplitude of the piezoelectric terminal, and the conduction time of the switch is affected by the inductance, capacitance of the piezoelectric terminal, Even under the influence of the load, the precise control of the conduction time requires additional manual adjustment, and an inappropriate switch conduction time will greatly reduce the extraction efficiency of the rectifier. Considering these issues, this circuit is not suitable for small piezoelectric energy harvesting.

发明内容Contents of the invention

为解决上述技术问题，本发明提出了一种开路式优化翻转时间的压电能量采集整流器。解决方案为：一种开路式优化翻转时间的压电能量采集整流器。该整流器包括两个带使能端的有源二极管，其被连接以检测流经的电流从正到负的过零点，一旦电流过零点，关断该二极管，使能与之相对的有源二极管，改变一位开关状态信号，该信号作为有源二极管的输出被送到数字电路控制模块的输入端和相对的二极管的使能端；以及一个峰值检测及数字电路控制模块，其被连接以接收所述有源二极管的开关状态信号，并检测出现在有源二极管阴极端的电压峰值，或压电器件两端的电压峰值，输出优化脉宽的脉冲信号被送到开关的输入控制端；以及两个开关，其被连接到数字电路控制模块的输出端以接收所述峰值检测及数字电路控制模块的脉冲信号，完成导通/截止操作；以及一个电感，其与压电器件串联以在压电器件输出电流过零点时与压电端电容、负载一起形成一个谐振腔，向负载传输能量的同时帮助翻转压电器件的电容电压，该电感一端与压电设备一端相连，电感的另一端与所述的一个有源二极管的阴极和一个开关的一端相连，压电设备的另一端分别与所述的另一个有源二极管的阴极和另一个开关的一端相连，两个开关的另一端相连接到负载，两个有源二级管的阳极相连接到地。In order to solve the above technical problems, the present invention proposes an open-circuit piezoelectric energy harvesting rectifier with optimized flipping time. The solution: an open-circuit piezoelectric energy-harvesting rectifier with optimized flipping time. The rectifier includes two active diodes with enabling terminals, which are connected to detect the zero crossing point of the current flowing from positive to negative, once the current crosses zero point, turn off the diode and enable the opposite active diode, changing a switch state signal, the signal is sent to the input terminal of the digital circuit control module and the enable terminal of the corresponding diode as the output of the active diode; and a peak detection and digital circuit control module, which is connected to receive the The switching status signal of the active diode is detected, and the peak voltage appearing at the cathode terminal of the active diode or the voltage peak value at both ends of the piezoelectric device is detected, and a pulse signal with an optimized pulse width is output and sent to the input control terminal of the switch; and two A switch, which is connected to the output terminal of the digital circuit control module to receive the peak detection and the pulse signal of the digital circuit control module, to complete the on/off operation; and an inductor, which is connected in series with the piezoelectric device to connect the piezoelectric device When the output current crosses the zero point, it forms a resonant cavity together with the piezoelectric terminal capacitor and the load, which helps to reverse the capacitor voltage of the piezoelectric device while transmitting energy to the load. One end of the inductor is connected to one end of the piezoelectric device, and the other end of the inductor is connected to the The cathode of one active diode is connected to one end of a switch, the other end of the piezoelectric device is respectively connected to the cathode of the other active diode and one end of another switch, and the other ends of the two switches are connected to the load , the anodes of the two active diodes are connected to ground.

本发明提出的优化翻转时间的压电能量采集整流器，优点在于：The piezoelectric energy harvesting rectifier with optimized inversion time proposed by the present invention has the advantages of:

1.将串联电感同步开关能量采集技术融入全桥整流器结构中，相对于传统串联电感同步开关能量采集技术，减少了一个开关元件，减低了硬件成本。1. Integrating the series inductor synchronous switch energy harvesting technology into the full bridge rectifier structure, compared with the traditional series inductor synchronous switch energy harvesting technology, one switching element is reduced and the hardware cost is reduced.

2.使用整流器中有源二极管和开关而不是被动二极管大大地降低了前向电压降。2. Using active diodes and switches in the rectifier instead of passive diodes greatly reduces the forward voltage drop.

3.能够自动检测电感电流过零点，实现零电流开关，并且同步开关具有一个优化的开关导通时长。3. It can automatically detect the zero-crossing point of the inductor current to realize zero-current switching, and the synchronous switch has an optimized switch on-time.

4.有一个简单低功耗的数字电路控制模块，其降低了使用电感同步开关能量采集技术所带来的额外的功耗，从而增加了负载端或者储能端的净能量。4. There is a simple and low-power digital circuit control module, which reduces the extra power consumption caused by the use of inductive synchronous switching energy harvesting technology, thereby increasing the net energy at the load end or energy storage end.

附图说明Description of drawings

图1是典型的使用全桥整流器的压电能量采集电路及相应结点波形示意图；Figure 1 is a typical piezoelectric energy harvesting circuit using a full-bridge rectifier and a schematic diagram of the corresponding node waveforms;

图2是典型的使用串联电感同步开关能量采集技术的压电能量采集电路和相应结点波形示意图；Figure 2 is a schematic diagram of a typical piezoelectric energy harvesting circuit using a series inductor synchronous switching energy harvesting technology and corresponding node waveforms;

图3是本发明公开的开路式优化翻转时间的压电能量采集整流器；FIG. 3 is an open-circuit piezoelectric energy harvesting rectifier with optimized flipping time disclosed by the present invention;

图4是本发明公开的整流器关键结点的波形时序示意图；Fig. 4 is a schematic diagram of the waveform timing of the key nodes of the rectifier disclosed in the present invention;

具体实施方式detailed description

以下结合附图和具体实施对本发明做进一步详细说明。The present invention will be described in further detail below in conjunction with the accompanying drawings and specific implementation.

如图1、图2和图3所示，压电传导器被等效为一个电路模型，该电路模型包括并联的一个电流源i_P、一个电阻R_P和一个电容C_P。假设电流源可以表示为As shown in Fig. 1, Fig. 2 and Fig. 3, the piezoelectric conductor is equivalent to a circuit model, which includes a current source i _P , a resistor R _P and a capacitor C _P connected in parallel. Suppose the current source can be expressed as

i_P＝I_Psin(2πf_Pt)(1)i _P ＝I _P sin(2πf _P t)(1)

其中电流幅度I_P与振动源的加速度大小相关，f_P对应振动源的振动频率。此外，因为电阻R_P的值很大在兆级别，所以在分析中可以忽略，并且假设负载电容C_L的值很大，使得V_RECT可以看成一个稳定的直流电压。Among them, the current amplitude I _P is related to the acceleration of the vibration source, and f _P corresponds to the vibration frequency of the vibration source. In addition, because the value of the resistance R _P is very large in the mega-level, it can be ignored in the analysis, and the value of the load capacitance C _L is assumed to be large, so that V _RECT can be regarded as a stable DC voltage.

图3所示为本发明的整流器，其基本运行原理可以参考图4，在t3时刻之前，二极管D1被打开，D2被关断，S1和S2都截止，B点电压V_B由于i_P充电逐渐上升，当其上升到峰值时，也即i_P在从正到负过零点附近时，开关S2导通，一个经过路径A-B-V_RECT-C-D的谐振腔形成。储存在电容C_P中的一部分能量通过该路径传输到负载，另一部分到电感L中，然后电感中的能量被传回到电容C_P中，并在其两端产生一个翻转的电压。由于此时D1位于谐振环路中，电流只能沿A→B→V_RECT→C→D的方向流动；当电感中的所有能量传回C_P后，电容电压翻转过程自动终止。一旦在t4时刻完成翻转，D1被关断，S2再次截止，D2被打开。反向电流i_P对电容充电，V_D或者V_A电压逐渐上升直到检测到D或者A点电压达到峰值。同样的工作原理，在i_P的负半周期重复其正半周期时的相似的运行操作。并在下个电流周期重复整个过程。Figure 3 shows the rectifier of the present invention, its basic operating principle can refer to Figure 4, before the time t3, the diode D1 is turned on, D2 is turned off, both S1 and S2 are cut off, the voltage V _B of point B is gradually charged due to i _P When it rises to the peak value, that is, when i _P is near the zero crossing point from positive to negative, the switch S2 is turned on, and a resonant cavity passing through the path ABV _RECT -CD is formed. Part of the energy stored in the capacitor C _P is transmitted to the load through this path, and the other part is sent to the inductor L, and then the energy in the inductor is transferred back to the capacitor C _P , and an inverted voltage is generated across it. Since D1 is in the resonant loop at this time, the current can only flow in the direction of A→B→ _VRECT →C→D; when all the energy in the inductor is transferred back to C _P , the capacitor voltage reversal process is automatically terminated. Once the flip is completed at t4, D1 is turned off, S2 is turned off again, and D2 is turned on. The reverse current i _P charges the capacitor, and the voltage of V _D or VA gradually rises until it detects that the voltage at point D or _A reaches a peak value. The same working principle, similar operation when the negative half cycle of _iP repeats its positive half cycle. And repeat the whole process in the next current cycle.

图1所示的典型整流器的输出功率可以表示为The output power of a typical rectifier shown in Figure 1 can be expressed as

${P P}_{L L,, F f B B} = = 22 {V V}_{R R E E. C C T T} ((\frac{{I I}_{P P}}{π π} - - 22 {C C}_{P P} {V V}_{R R E E. C C T T} {f f}_{P P} - - 44 {C C}_{P P} {V V}_{D D.} {f f}_{P P})) - - - - - - ((22))$

其中V_D为被动二极管的前向电压降。通过式(2)可以得出负载端可获得的最大功率为where V _D is the forward voltage drop of the passive diode. Through formula (2), it can be concluded that the maximum power available at the load end is

${P P}_{L L,, F f B B} ((m m a a x x)) = = {C C}_{P P} {f f}_{P P} {((\frac{{I I}_{P P}}{22 {πf πf}_{P P} {C C}_{P P}} - - 22 {V V}_{D D.}))}^{22} - - - - - - ((33))$

此时 $V_{R E C T} = \frac{I_{P}}{4 {πf}_{P} C_{P}} - V_{D} .$ at this time $V_{R E. C T} = \frac{I_{P}}{4 {πf}_{P} C_{P}} - V_{D.} .$

而本发明的整流器因采用有源二极管和开关，前向电压降可以忽略不计。每次开关S1或者S2短暂闭合，储存在电容C_P的一部分能量被传递到负载端，另一部分能量用来翻转电容C_P的电压。其他时间段，开关S1和S2都截止，压电端与负载端断开，式(4)给出了在此时间段内电压V_M与V_m之间的关系，参照图3，V_M与V_m分别对应于翻转事件前、后的电压。However, since the rectifier of the present invention adopts active diodes and switches, the forward voltage drop can be ignored. Each time the switch S1 or S2 is briefly closed, a part of the energy stored in the capacitor C _P is transferred to the load terminal, and another part of the energy is used to reverse the voltage of the capacitor C _P. In other time periods, both switches S1 and S2 are cut off, and the piezoelectric terminal is disconnected from the load terminal. Equation (4) shows the relationship between voltage V _M and V _m during this time period. Referring to Figure 3, V _M and V _m corresponds to the voltage before and after the flipping event, respectively.

$| | {V V}_{M m} | | = = | | {V V}_{m m} | | + + \frac{22 {I I}_{P P}}{{ωC ω C}_{P P}} - - - - - - ((44))$

每次翻转，压电输入端输出的能量为For each flip, the energy output from the piezo input is

${V V}_{R R E E. C C T T} {&Integral; &Integral;}_{00}^{T T / / 22} I I d d t t = = {V V}_{R R E E. C C T T} {C C}_{p p} (({V V}_{M m} + + {V V}_{m m})) = = \frac{π π}{{R R}_{L L} ω ω} {V V}_{R R E E. C C T T}^{22} - - - - - - ((55))$

参照图4，定义η为重置电压差与翻转电压差的比值，Referring to Figure 4, define η as the ratio of the reset voltage difference to the flipping voltage difference,

$η η = = \frac{| | {V V}_{m m} | | + + {V V}_{R R E E. C C T T}}{| | {V V}_{M m} | | - - {V V}_{R R E E. C C T T}} - - - - - - ((66))$

通过(4)、(5)和(6)可以获得负载端的输出直流电压V_RECT为Through (4), (5) and (6), the output DC voltage V _RECT at the load terminal can be obtained as

${V V}_{R R E E. C C T T} = = \frac{22 {R R}_{L L} {I I}_{p p} ((11 + + η η))}{π π ((11 - - η η)) + + 22 {R R}_{L L} {C C}_{p p} ω ω ((11 + + η η))} - - - - - - ((77))$

因其输出功率可表达为Since its output power can be expressed as

${P P}_{L L} = = \frac{{V V}_{R R E E. C C T T}^{22}}{{R R}_{L L}} - - - - - - ((88))$

对式(8)求导，可得到最大的输出功率为Deriving formula (8), the maximum output power can be obtained as

${P P}_{L L,, S S E E. R R} ((m m a a x x)) = = \frac{11 + + η η}{11 - - η η} \cdot \cdot \frac{{I I}_{p p}^{22}}{22 {πC πC}_{p p} ω ω} - - - - - - ((99))$

此时最优的负载电阻和最优输出直流电压分别为At this time, the optimal load resistance and the optimal output DC voltage are respectively

${R R}_{L L,, O o P P T T} = = \frac{11 - - η η}{11 + + η η} \cdot \cdot \frac{π π}{22 {C C}_{p p} ω ω},, {V V}_{R R E E. C C T T,, O o P P T T} = = \frac{{I I}_{p p}}{22 {ωC ω C}_{p p}} - - - - - - ((1010))$

采用一组合理的参数如I_P＝100μA，f_P＝100Hz,，C_P＝20nF，η＝0.7，V_D＝0.7代入式(3)和式(9)。二极管全桥最大输出功率为86μW，采用本发明的最大输出功率为717μW，大约是二极管全桥最大输出功率的8倍。A set of reasonable parameters such as I _P =100 μA, f _P =100 Hz, C _P =20 nF, η =0.7, V _D =0.7 are substituted into formula (3) and formula (9). The maximum output power of the diode full bridge is 86 μW, and the maximum output power of the present invention is 717 μW, which is about 8 times of the maximum output power of the diode full bridge.

综上所述，本发明公开的整流器有一种新颖的电路结构，该结构融入了串联电感同步开关能量采集技术，并且有一个简单的控制电路控制压电能量采集器的电容电压最优化翻转，加上有源二极管和开关的使用，最终有效地增加了负载端或者储能端的净能量。To sum up, the rectifier disclosed in the present invention has a novel circuit structure, which incorporates the series inductor synchronous switch energy harvesting technology, and has a simple control circuit to control the optimal flipping of the capacitor voltage of the piezoelectric energy harvester, adding The use of active diodes and switches ultimately effectively increases the net energy at the load or storage end.

虽然本发明已相对有限数量的实施例进行了描述，但受益于此公开的本领域的技术人员将理解由此产生的多种修改和变化。所附权利要求旨在涵盖属于本发明真正精神和范围的此类修改和变化。While the invention has been described with respect to a limited number of embodiments, various modifications and changes therefrom will become apparent to those skilled in the art having the benefit of this disclosure. The appended claims are intended to cover such modifications and changes as fall within the true spirit and scope of the invention.

Claims

1. open type optimizes the piezoelectric energy collection commutator of flip-flop transition, including:

Two active diodes with Enable Pin, it is connected to detect the electric current that flows through zero crossing from positive to negative, once current zero-crossing point, turn off this diode, enable active diode on the other side, and changing the One-position switch status signal of its output, this signal is sent to the input of Digital Circuit Control module and the Enable Pin of relative diode as the output of active diode; And

One peakvalue's checking and Digital Circuit Control module, it is coupled to receive the switch state signal of described active diode, and detect the voltage peak now with source diode cathode terminal, or the voltage peak at piezoelectric device two ends, the pulse signal of output optimization pulsewidth is sent to the input of switch and controls end; And

Two switches, it is connected to the outfan of Digital Circuit Control module to receive described peakvalue's checking and the pulse signal of Digital Circuit Control module, completes conduction and cut-off operation; And

One inductance, its connect with piezoelectric device with piezoelectric device export current zero-crossing point time with piezoelectricity end electric capacity, load collectively forms a resonator cavity, while Load transportation energy, help to overturn the capacitance voltage of piezoelectric device, this inductance one end is connected with piezoelectric device one end, the other end of inductance is connected with the negative electrode of described active diode and one end of a switch, the other end of piezoelectric device is connected with the negative electrode of another described active diode and one end of another switch, the other end of two switches is connected to load, the anode of two active diodes is connected to ground.

2. active diode as claimed in claim 1 is the diode of a pair complementary conduction and cut-off, when its cathode voltage is higher than anode, active diode ends, switch state signal is output as a high level, relative active diode conducting, when cathode voltage is lower than anode, active diode turns on, switch state signal is output as a low level, relative active diode cut-off.

3. switching as claimed in claim 1, before peakvalue's checking and digital circuit blocks detect voltage peak, two switches all end, once voltage peak be detected, and a switch conduction corresponding with this voltage.

4. peakvalue's checking as claimed in claim 1 and Digital Circuit Control module, when voltage peak being detected, the level upset of the output signal of its correspondence, a corresponding switch conduction, active diode switch state signal automatic turning subsequently, the change of this signal is once detected, and output is flipped back to former level, switch cut-off again.